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#4472940 - 07/28/17 10:58 AM Assessing fluid temps on track
dparm Offline


Registered: 04/19/10
Posts: 13466
Loc: Chicago, IL
The C7 Corvette has the Cosworth-developed Performance Data Recorder and associated analysis software, so I can see detailed vehicle health stats when I take it out on the track. Here is the data it provides for the "vehicle health".

I am trying to ascertain if any of these seem too high or if they would warrant a much shorter change interval. I've never had this level of data available before and am seeking advice on how to adjust my maintenance intervals and product selection, if at all.

Note: ambient temps were about 80 F on this day and the session was about 30 minutes long. These values are pretty close to what I've seen on other track days.


Quote:
Coolant:
Min: 190 F
Max: 216 F


Engine oil (Mobil 1 5w30):
Min pressure: 28.4 psi
Max pressure: 46.4 psi

Min temperature: 187 F
Max temperature: 264 F


Manual transmission (ACDelco Dexron III):
Min transmission oil temperature: 154 F
Max transmission oil temperature: 246 F
_________________________
2017 Chevrolet Corvette Grand Sport

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#4472954 - 07/28/17 11:10 AM Re: Assessing fluid temps on track [Re: dparm]
Canadastang Offline


Registered: 12/08/15
Posts: 261
Loc: Ontario Canada
IMO those temps look great.

How long are the sessions? 20 mins?

Is there a lot of traffic and waiting to pass on the track or is it 100% for the whole session?

The max oil temp I've seen in my car on track after 20 mins is about 250F, which for a good synthetic is no big deal.

Although I'm surprised the max oil pressure was only 46PSI, I guess I'm too used to modular Fords running 60PSI at cruise.

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#4472957 - 07/28/17 11:14 AM Re: Assessing fluid temps on track [Re: Canadastang]
dparm Offline


Registered: 04/19/10
Posts: 13466
Loc: Chicago, IL
Originally Posted By: Canadastang
IMO those temps look great.

How long are the sessions? 20 mins?

Is there a lot of traffic and waiting to pass on the track or is it 100% for the whole session?

The max oil temp I've seen in my car on track after 20 mins is about 250F, which for a good synthetic is no big deal.

Although I'm surprised the max oil pressure was only 46PSI, I guess I'm too used to modular Fords running 60PSI at cruise.



Sessions are 30 minutes long, but that includes an "out" (warm-up) lap and an "in" (cool down) lap, so it's more like 25 minutes of actual hard driving assuming no other issues. The car sits for 60-90 minutes between sessions.

Sometimes you will get held up by traffic, sure, but it's rarely more than 60 seconds. In the worst cases, it might be 90 seconds. If there's a yellow flag or similar incident, you might slow down for 15-30 seconds.

The Corvette has a dry sump system with computer controlled oil pumps, so the oil pressures are remarkably stable.

My M3 used to push similar oil temps, but I am more curious about the transmission temps. It's a 7-speed transaxle running Dexron III ATF.
_________________________
2017 Chevrolet Corvette Grand Sport

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#4472962 - 07/28/17 11:18 AM Re: Assessing fluid temps on track [Re: dparm]
Canadastang Offline


Registered: 12/08/15
Posts: 261
Loc: Ontario Canada
Off topic here, but do you find the GS is lacking anything on track or is ready to go right out of the box?

Do you swap brake pads before track days?

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#4472970 - 07/28/17 11:27 AM Re: Assessing fluid temps on track [Re: Canadastang]
dparm Offline


Registered: 04/19/10
Posts: 13466
Loc: Chicago, IL
Originally Posted By: Canadastang
Off topic here, but do you find the GS is lacking anything on track or is ready to go right out of the box?

Do you swap brake pads before track days?



The car is 99% ready to go in stock form.

The OEM brake pads wore out very fast (just two track days) but performed fine. I swapped them for a more aggressive but still streetable pad, the Ferodo DS2500. No need to change pads at the track.

I may add a harness bar and 6-point harness later this summer. The braking Gs are immense and being able to use a HANS would be nice too.
_________________________
2017 Chevrolet Corvette Grand Sport

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#4472996 - 07/28/17 11:54 AM Re: Assessing fluid temps on track [Re: dparm]
SteveSRT8 Offline


Registered: 10/10/08
Posts: 18953
Loc: Sunny Florida
I was assured by M1 folks that 300 degrees was still well below their maximum allowable temps with 0W-40 in the sump. Not sure what Chevy says but no reason to imagine those trans temps are too high either. Too bad GM isn't as accessible as the SRT guys. They have regular chats at the busy forums and can really get you those "insider" facts.

I am almost certain that car has synthetic transmission lubricant from the factory.

BTW, that integrated data logging is outrageous on paper. Made any graphs yet to share?
_________________________
"In a democracy, dissent is an act of faith."
J. William Fulbright
Best ET-12.79 @ 111 mph
4340 pounds, Street tires
Just like we go to Publix

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#4473094 - 07/28/17 02:13 PM Re: Assessing fluid temps on track [Re: SteveSRT8]
dparm Offline


Registered: 04/19/10
Posts: 13466
Loc: Chicago, IL
Originally Posted By: SteveSRT8
I was assured by M1 folks that 300 degrees was still well below their maximum allowable temps with 0W-40 in the sump. Not sure what Chevy says but no reason to imagine those trans temps are too high either. Too bad GM isn't as accessible as the SRT guys. They have regular chats at the busy forums and can really get you those "insider" facts.

I am almost certain that car has synthetic transmission lubricant from the factory.

BTW, that integrated data logging is outrageous on paper. Made any graphs yet to share?



GM has competition/track driving recommendations, but some of it seems vague or contradictory. Even their chief engineer, when asked on the Corvette Forums website, wasn't giving the clearest answers. They specify shorter change intervals which I plan to stick to. The only time they specify a different fluid is for the engine oil: Mobil 1 15w50, and for "hot" climates.

I have been looking at the graphs of my laps, yeah. It's been useful to see where I've been faster and slower throughout different portions of the track, e.g. I lose a 1/2 second by not fully tracking out at corner X. It is a lot of data to look at, so I've been taking it slowly and making minor adjustments. My lap times are slowly coming down.
_________________________
2017 Chevrolet Corvette Grand Sport

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#4477702 - 08/02/17 07:32 PM Re: Assessing fluid temps on track [Re: dparm]
A_Harman Offline


Registered: 10/01/10
Posts: 6920
Loc: Michigan
Originally Posted By: dparm
The C7 Corvette has the Cosworth-developed Performance Data Recorder and associated analysis software, so I can see detailed vehicle health stats when I take it out on the track. Here is the data it provides for the "vehicle health".

I am trying to ascertain if any of these seem too high or if they would warrant a much shorter change interval. I've never had this level of data available before and am seeking advice on how to adjust my maintenance intervals and product selection, if at all.

Note: ambient temps were about 80 F on this day and the session was about 30 minutes long. These values are pretty close to what I've seen on other track days.


Quote:
Coolant:
Min: 190 F
Max: 216 F


Engine oil (Mobil 1 5w30):
Min pressure: 28.4 psi
Max pressure: 46.4 psi

Min temperature: 187 F
Max temperature: 264 F


Manual transmission (ACDelco Dexron III):
Min transmission oil temperature: 154 F
Max transmission oil temperature: 246 F


Those all look like good numbers. Does the PDR allow you to make graphs of the different channels versus time?
It would be nice to see if that min oil pressure is occurring in left-hand turns. (Like on my 'vette, albeit with wet-sump oiling.) Mine can be counted on to dip down to 18-20 psi in long left-hand turns.
_________________________
1985 Z51 Corvette track car
2002 Camaro Z28 LS1/6-speed
2001 Dodge Ram 2500 diesel
1972 GMC 1500 shortbed project truck

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#4478361 - 08/03/17 04:18 PM Re: Assessing fluid temps on track [Re: dparm]
dparm Offline


Registered: 04/19/10
Posts: 13466
Loc: Chicago, IL
No, I don't see a way to graph those over time. I can only see the min/max of each for a given lap. They're pretty steady (within a few %) after the warm-up lap, which is a good sign. The only one that seems to rise from the warm-up lap until the very end is the transmission temp, but regardless of the day I race on, the maximum still holds the same.

Given that the OLM is showing just under 50% remaining after only 3500 miles/4 track days, I am considering having them change it next week when I'm at the dealer. It's a free change so I figure why not. Yes/no?
_________________________
2017 Chevrolet Corvette Grand Sport

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#4478744 - 08/04/17 06:14 AM Re: Assessing fluid temps on track [Re: dparm]
SteveSRT8 Offline


Registered: 10/10/08
Posts: 18953
Loc: Sunny Florida
Yes. Note that my dealer here would not change an OLM equipped car or truck until 15% or less OLM reading. But yes, if it's a track day clean oil can't hurt much!

GM likes hot fluids, and none of yours seem to be outside of the allowable temps with modern fluids...
_________________________
"In a democracy, dissent is an act of faith."
J. William Fulbright
Best ET-12.79 @ 111 mph
4340 pounds, Street tires
Just like we go to Publix

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